Method and device for transmitting/receiving wireless signal in wireless communication system

ABSTRACT

The present invention relates to a wireless communication system, and specifically, to a method and a device for the method which comprises the steps of: receiving a PDCCH including uplink scheduling information; and transmitting, at a UL SF, a PUSCH indicated by the uplink scheduling information, wherein, if the PDCCH requests a transmission of an ACK, the PUSCH includes ACK information about a SF set corresponding to the UL SF, wherein the SF set includes a plurality of SFs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/074,599, filed on Aug. 1, 2018, which is a National Phase ofPCT/KR2017/001157, filed on Feb. 2, 2017, which claims priority under 35U.S.C. § 119(e) to U.S. Provisional Application Nos. 62/289,938;62/309,972; 62/319,295; 62/327,431; 62/331,481; 62/353,117; and62/437,040 filed respectively on Feb. 2, 2016; Mar. 18, 2016; Apr. 7,2016; Apr. 25, 2016; May 4, 2016; Jun. 22, 2016; and Dec. 20, 2016, allof which are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting/receivinga wireless signal. The wireless communication system includes a CA-based(Carrier Aggregation-based) wireless communication system.

BACKGROUND ART

Generally, a wireless communication system is developing to diverselycover a wide range to provide such a communication service as an audiocommunication service, a data communication service and the like. Thewireless communication is a sort of a multiple access system capable ofsupporting communications with multiple users by sharing availablesystem resources (e.g., bandwidth, transmit power, etc.). For example,the multiple access system may include one of CDMA (code divisionmultiple access) system, FDMA (frequency division multiple access)system, TDMA (time division multiple access) system, OFDMA (orthogonalfrequency division multiple access) system, SC-FDMA (single carrierfrequency division multiple access) system and the like.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method of efficientlytransmitting/receiving control information in a wireless communicationand an apparatus therefor.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

In one aspect of the present invention, there is provided a method ofperforming communication by a UE in a wireless communication system,including: receiving a physical downlink control channel (PDCCH)including uplink scheduling information; and transmitting, in an uplinksubframe (UL SF), a physical uplink shared channel (PUSCH) indicated bythe uplink scheduling information, wherein, if the PDCCH requests ACKtransmission, the PUSCH includes ACK information about an SF setcorresponding to the UL SF, the SF set including a plurality of SFs.

In another aspect of the present invention, there is provided a UE usedin a wireless communication system, including a radio frequency (RF)module and a processor, wherein the processor is configured to receive aPDCCH including uplink scheduling information and to transmit, in a ULSF, a PUSCH indicated by the uplink scheduling information, wherein, ifthe PDCCH requests ACK transmission, the PUSCH includes ACK informationabout an SF set corresponding to the UL SF, the SF set including aplurality of SFs.

Preferably, if the PDCCH does not request ACK transmission, the PUSCHmay not include the ACK information about the SF set corresponding tothe UL SF.

Preferably, the SF set may include a plurality of consecutive SFs.

Preferably, the SF set may include a plurality of SFs corresponding to aplurality of HARQ process IDs.

Preferably, the SF set may include a plurality of SFs corresponding to aplurality of downlink assignment indices (DAIs).

Preferably, the scheduling information may include schedulinginformation about a plurality of PUSCHs, the PDCCH may further includeACK request information, and the ACK request information may be appliedonly to an initially scheduled PUSCH among the plurality of PUSCHs.

Preferably, UL and DL transmission resources may be aperiodicallyconfigured in the wireless communication system.

Advantageous Effects

According to the present invention, wireless signal transmission andreception can be efficiently performed in a wireless communicationsystem.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 illustrates physical channels used in 3GPP LTE (-A) and a signaltransmission method using the same.

FIG. 2 illustrates a radio frame structure.

FIG. 3 illustrates a resource grid of a downlink slot.

FIG. 4 illustrates a downlink subframe structure.

FIG. 5 illustrates an example of an Enhanced Physical Downlink ControlChannel (EPDCCH).

FIG. 6 illustrates the structure of an uplink subframe used in LTE (-A).

FIG. 7 illustrates UL HARQ (Uplink Hybrid Automatic Repeat reQuest)operation.

FIG. 8 illustrates a method of performing an ACK/NACK transmissionprocedure using a DAI (Downlink Assignment Index).

FIG. 9 illustrates a carrier aggregation (CA)-based wirelesscommunication system.

FIG. 10 illustrates cross-carrier scheduling.

FIG. 11 illustrates carrier aggregation of a licensed band and anunlicensed band.

FIGS. 12 and 13 illustrate a method of occupying resources within anunlicensed band.

FIGS. 14 and 15 illustrate an ACK/NACK transmission procedure accordingto the present invention.

FIG. 16 illustrates a base station and a user equipment applicable to anembodiment of the present invention.

BEST MODE

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as code division multiple access(CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), orthogonal frequency division multiple access(OFDMA), and single carrier frequency division multiple access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, and EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3rd Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) evolves from 3GPP LTE. While the following description is given,centering on 3GPP LTE/LTE-A for clarity, this is purely exemplary andthus should not be construed as limiting the present invention.

In a wireless communication system, a user equipment (UE) receivesinformation through downlink (DL) from a base station (BS) and transmitinformation to the BS through uplink (UL). The information transmittedand received by the BS and the UE includes data and various controlinformation and includes various physical channels according totype/usage of the information transmitted and received by the UE and theBS.

FIG. 1 illustrates physical channels used in 3GPP LTE (-A) and a signaltransmission method using the same.

When powered on or when a UE initially enters a cell, the UE performsinitial cell search involving synchronization with a BS in step S101.For initial cell search, the UE synchronizes with the BS and acquireinformation such as a cell Identifier (ID) by receiving a primarysynchronization channel (P-SCH) and a secondary synchronization channel(S-SCH) from the BS. Then the UE may receive broadcast information fromthe cell on a physical broadcast channel (PBCH). In the mean time, theUE may check a downlink channel status by receiving a downlink referencesignal (DL RS) during initial cell search.

After initial cell search, the UE may acquire more specific systeminformation by receiving a physical downlink control channel (PDCCH) andreceiving a physical downlink shared channel (PDSCH) based oninformation of the PDCCH in step S102.

The UE may perform a random access procedure to access the BS in stepsS103 to S106. For random access, the UE may transmit a preamble to theBS on a physical random access channel (PRACH) (S103) and receive aresponse message for preamble on a PDCCH and a PDSCH corresponding tothe PDCCH (S104). In the case of contention-based random access, the UEmay perform a contention resolution procedure by further transmittingthe PRACH (S105) and receiving a PDCCH and a PDSCH corresponding to thePDCCH (S106).

After the foregoing procedure, the UE may receive a PDCCH/PDSCH (S107)and transmit a physical uplink shared channel (PUSCH)/physical uplinkcontrol channel (PUCCH) (S108), as a general downlink/uplink signaltransmission procedure. Control information transmitted from the UE tothe BS is referred to as uplink control information (UCI). The UCIincludes hybrid automatic repeat and requestacknowledgement/negative-acknowledgement (HARQ-ACK/NACK), schedulingrequest (SR), channel state information (CSI), etc. The CSI includes achannel quality indicator (CQI), a precoding matrix indicator (PMI), arank indicator (RI), etc. While the UCI is transmitted on a PUCCH ingeneral, the UCI may be transmitted on a PUSCH when control informationand traffic data need to be simultaneously transmitted. In addition, theUCI may be aperiodically transmitted through a PUSCH according torequest/command of a network.

FIG. 2 illustrates a radio frame structure. Uplink/downlink data packettransmission is performed on a subframe-by-subframe basis. A subframe isdefined as a predetermined time interval including a plurality ofsymbols. 3GPP LTE supports a type-1 radio frame structure applicable tofrequency division duplex (FDD) and a type-2 radio frame structureapplicable to time division duplex (TDD).

FIG. 2(a) illustrates a type-1 radio frame structure. A downlinksubframe includes 10 subframes each of which includes 2 slots in thetime domain. A time for transmitting a subframe is defined as atransmission time interval (TTI). For example, each subframe has aduration of 1 ms and each slot has a duration of 0.5 ms. A slot includesa plurality of OFDM symbols in the time domain and includes a pluralityof resource blocks (RBs) in the frequency domain. Since downlink usesOFDM in 3GPP LTE, an OFDM symbol represents a symbol period. The OFDMsymbol may be called an SC-FDMA symbol or symbol period. An RB as aresource allocation unit may include a plurality of consecutivesubcarriers in one slot.

The number of OFDM symbols included in one slot may depend on cyclicprefix (CP) configuration. CPs include an extended CP and a normal CP.When an OFDM symbol is configured with the normal CP, for example, thenumber of OFDM symbols included in one slot may be 7. When an OFDMsymbol is configured with the extended CP, the length of one OFDM symbolincreases, and thus the number of OFDM symbols included in one slot issmaller than that in case of the normal CP. In case of the extended CP,the number of OFDM symbols allocated to one slot may be 6. When achannel state is unstable, such as a case in which a UE moves at a highspeed, the extended CP can be used to reduce inter-symbol interference.

When the normal CP is used, one subframe includes 14 OFDM symbols sinceone slot has 7 OFDM symbols. The first three OFDM symbols at most ineach subframe can be allocated to a PDCCH and the remaining OFDM symbolscan be allocated to a PDSCH.

FIG. 2(b) illustrates a type-2 radio frame structure. The type-2 radioframe includes 2 half frames. Each half frame includes 4(5) normalsubframes and 10 special subframes. The normal subframes are used foruplink or downlink according to UL-DL configuration. A subframe iscomposed of 2 slots.

Table 1 shows subframe configurations in a radio frame according toUL-DL configurations.

TABLE 1 Uplink- Downlink- downlink to-Uplink config- Switch pointSubframe number uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U UD S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 msD S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is used for initial cell search, synchronization orchannel estimation in a UE and UpPTS is used for channel estimation in aBS and uplink transmission synchronization in a UE. The GP eliminates ULinterference caused by multi-path delay of a DL signal between a UL anda DL.

The radio frame structure is merely exemplary and the number ofsubframes included in the radio frame, the number of slots included in asubframe, and the number of symbols included in a slot can be vary.

FIG. 3 illustrates a resource grid of a downlink slot.

Referring to FIG. 3, a downlink slot includes a plurality of OFDMsymbols in the time domain. While one downlink slot may include 7 OFDMsymbols and one resource block (RB) may include 12 subcarriers in thefrequency domain in the figure, the present invention is not limitedthereto. Each element on the resource grid is referred to as a resourceelement (RE). One RB includes 12×7 REs. The number NRB of RBs includedin the downlink slot depends on a downlink transmit bandwidth. Thestructure of an uplink slot may be same as that of the downlink slot.

FIG. 4 illustrates a downlink subframe structure.

Referring to FIG. 4, a maximum of three (four) OFDM symbols located in afront portion of a first slot within a subframe correspond to a controlregion to which a control channel is allocated. The remaining OFDMsymbols correspond to a data region to which a physical downlink sharedchancel (PDSCH) is allocated. A basic resource unit of the data regionis an RB. Examples of downlink control channels used in LTE include aphysical control format indicator channel (PCFICH), a physical downlinkcontrol channel (PDCCH), a physical hybrid ARQ indicator channel(PHICH), etc. The PCFICH is transmitted at a first OFDM symbol of asubframe and carries information regarding the number of OFDM symbolsused for transmission of control channels within the subframe. The PHICHis a response of uplink transmission and carries a HARQ acknowledgment(ACK)/negative-acknowledgment (NACK) signal. Control informationtransmitted through the PDCCH is referred to as downlink controlinformation (DCI). The DCI includes uplink or downlink schedulinginformation or an uplink transmit power control command for an arbitraryUE group.

Control information transmitted through the PDCCH is referred to asdownlink control information (DCI). Formats 0, 3, 3A and 4 for uplinkand formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B and 2C for downlink are definedas DCI formats. Information field type, the number of informationfields, the number of bits of each information field, etc. depend on DICformat. For example, the DCI formats selectively include informationsuch as hopping flag, RB assignment, MCS (Modulation Coding Scheme), RV(Redundancy Version), NDI (New Data Indicator), TPC (Transmit PowerControl), HARQ process number, PMI (Precoding Matrix Indicator)confirmation as necessary. Accordingly, the size of control informationmatched to a DCI format depends on the DCI format. An arbitrary DCIformat may be used to transmit two or more types of control information.For example, DIC formats 0/1A is used to carry DCI format 0 or DICformat 1, which are discriminated from each other using a flag field.

A PDCCH may carry a transport format and a resource allocation of adownlink shared channel (DL-SCH), resource allocation information of anuplink shared channel (UL-SCH), paging information on a paging channel(PCH), system information on the DL-SCH, information on resourceallocation of an upper-layer control message such as a random accessresponse transmitted on the PDSCH, a set of Tx power control commands onindividual UEs within an arbitrary UE group, a Tx power control command,information on activation of a voice over IP (VoIP), etc. A plurality ofPDCCHs can be transmitted within a control region. The UE can monitorthe plurality of PDCCHs. The PDCCH is transmitted on an aggregation ofone or several consecutive control channel elements (CCEs). The CCE is alogical allocation unit used to provide the PDCCH with a coding ratebased on a state of a radio channel. The CCE corresponds to a pluralityof resource element groups (REGs). A format of the PDCCH and the numberof bits of the available PDCCH are determined by the number of CCEs. TheBS determines a PDCCH format according to DCI to be transmitted to theUE, and attaches a cyclic redundancy check (CRC) to control information.The CRC is masked with a unique identifier (referred to as a radionetwork temporary identifier (RNTI)) according to an owner or usage ofthe PDCCH. If the PDCCH is for a specific UE, a unique identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. Alternatively,if the PDCCH is for a paging message, a paging identifier (e.g.,paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is forsystem information (more specifically, a system information block(SIB)), a system information RNTI (SI-RNTI) may be masked to the CRC.When the PDCCH is for a random access response, a random access-RNTI(RA-RNTI) may be masked to the CRC.

The PDCCH carries a message known as DCI which includes resourceassignment information and other control information for a UE or UEgroup. In general, a plurality of PDCCHs can be transmitted in asubframe. Each PDCCH is transmitted using one or more CCEs. Each CCEcorresponds to 9 sets of 4 REs. The 4 REs are referred to as an REG. 4QPSK symbols are mapped to one REG. REs allocated to a reference signalare not included in an REG, and thus the total number of REGs in OFDMsymbols depends on presence or absence of a cell-specific referencesignal. The concept of REG (i.e. group based mapping, each groupincluding 4 REs) is used for other downlink control channels (PCFICH andPHICH). That is, REG is used as a basic resource unit of a controlregion. 4 PDCCH formats are supported as shown in Table 2.

TABLE 2 Number Number PDCCH of CCEs Number of PDCCH format (n) of REGsbits 0 1 9 72 1 2 8 144 2 4 36 288 3 5 72 576

CCEs are sequentially numbered. To simplify a decoding process,transmission of a PDCCH having a format including n CCEs can be startedusing as many CCEs as a multiple of n. The number of CCEs used totransmit a specific PDCCH is determined by a BS according to channelcondition. For example, if a PDCCH is for a UE having a high-qualitydownlink channel (e.g. a channel close to the BS), only one CCE can beused for PDCCH transmission. However, for a UE having a poor channel(e.g. a channel close to a cell edge), 8 CCEs can be used for PDCCHtransmission in order to obtain sufficient robustness. In addition, apower level of the PDCCH can be controlled according to channelcondition.

LTE defines CCE positions in a limited set in which PDCCHs can bepositioned for each UE. CCE positions in a limited set that the UE needsto monitor in order to detect the PDCCH allocated thereto may bereferred to as a search space (SS). In LTE, the SS has a size dependingon PDCCH format. A UE-specific search space (USS) and a common searchspace (CSS) are separately defined. The USS is set per UE and the rangeof the CSS is signaled to all UEs. The USS and the CSS may overlap for agiven UE. In the case of a considerably small SS with respect to aspecific UE, when some CCEs positions are allocated in the SS, remainingCCEs are not present. Accordingly, the BS may not find CCE resources onwhich PDCCHs will be transmitted to available UEs within givensubframes. To minimize the possibility that this blocking continues tothe next subframe, a UE-specific hopping sequence is applied to thestarting point of the USS.

Table 3 shows sizes of the CSS and USS.

TABLE 3 Number of Number of Number candidates candidates PDCCH of CCEsin common in dedicated format (n) search space search space 0 1 — 6 1 2— 6 2 4 4 2 3 8 2 2

To control computational load of blind decoding based on the number ofblind decoding processes to an appropriate level, the UE is not requiredto simultaneously search for all defined DCI formats. In general, the UEsearches for formats 0 and 1A at all times in the USS. Formats 0 and 1Ahave the same size and are discriminated from each other by a flag in amessage. The UE may need to receive an additional format (e.g. format 1,1B or 2 according to PDSCH transmission mode set by a BS). The UEsearches for formats 1A and 1C in the CSS. Furthermore, the UE may beset to search for format 3 or 3A. Formats 3 and 3A have the same size asthat of formats 0 and 1A and may be discriminated from each other byscrambling CRC with different (common) identifiers rather than aUE-specific identifier. PDSCH transmission schemes and informationcontent of DCI formats according to transmission mode (TM) are arrangedbelow.

Transmission Mode (TM)

Transmission mode 1: Transmission from a single base station antennaport

Transmission mode 2: Transmit diversity

Transmission mode 3: Open-loop spatial multiplexing

Transmission mode 4: Closed-loop spatial multiplexing

Transmission mode 5: Multi-user MIMO (Multiple Input Multiple Output)

Transmission mode 6: Closed-loop rank-1 precoding

Transmission mode 7: Single-antenna port (port5) transmission

Transmission mode 8: Double layer transmission (ports 7 and 8) orsingle-antenna port (port 7 or 8) transmission

Transmission mode 9: Transmission through up to 8 layers (ports 7 to 14)or single-antenna port (port 7 or 8) transmission

DCI Format

Format 0: Resource grants for PUSCH transmission

Format 1: Resource assignments for single codeword PDSCH transmission(transmission modes 1, 2 and 7)

Format 1A: Compact signaling of resource assignments for single codewordPDSCH (all modes)

Format 1B: Compact resource assignments for PDSCH using rank-1 closedloop precoding (mod 6)

Format 1C: Very compact resource assignments for PDSCH (e.g.paging/broadcast system information)

Format 1D: Compact resource assignments for PDSCH using multi-user MIMO(mode 5)

Format 2: Resource assignments for PDSCH for closed-loop MIMO operation(mode 4)

Format 2A: Resource assignments for PDSCH for open-loop MIMO operation(mode 3)

Format 3/3A: Power control commands for PUCCH and PUSCH with 2-bit/1-bitpower adjustments

FIG. 5 illustrates an EPDCCH. The EPDCCH is a channel additionallyintroduced in LTE-A.

Referring to FIG. 5, a PDCCH (for convenience, legacy PDCCH or L-PDCCH)according to legacy LTE may be allocated to a control region (see FIG.4) of a subframe. In the figure, the L-PDCCH region means a region towhich a legacy PDCCH may be allocated. Meanwhile, a PDCCH may be furtherallocated to the data region (e.g., a resource region for a PDSCH). APDCCH allocated to the data region is referred to as an E-PDCCH. Asshown, control channel resources may be further acquired via the E-PDCCHto mitigate a scheduling restriction due to restricted control channelresources of the L-PDCCH region. Similarly to the L-PDCCH, the E-PDCCHcarries DCI. For example, the E-PDCCH may carry downlink schedulinginformation and uplink scheduling information. For example, the UE mayreceive the E-PDCCH and receive data/control information via a PDSCHcorresponding to the E-PDCCH. In addition, the UE may receive theE-PDCCH and transmit data/control information via a PUSCH correspondingto the E-PDCCH. The E-PDCCH/PDSCH may be allocated starting from a firstOFDM symbol of the subframe, according to cell type. In thisspecification, the PDCCH includes both L-PDCCH and EPDCCH unlessotherwise noted.

FIG. 6 illustrates a structure of an uplink subframe used in LTE (-A).

Referring to FIG. 6, a subframe 500 is composed of two 0.5 ms slots 501.Assuming a length of a normal cyclic prefix (CP), each slot is composedof 7 symbols 502 and one symbol corresponds to one SC-FDMA symbol. Aresource block (RB) 503 is a resource allocation unit corresponding to12 subcarriers in the frequency domain and one slot in the time domain.The structure of the uplink subframe of LTE (-A) is largely divided intoa data region 504 and a control region 505. A data region refers to acommunication resource used for transmission of data such as voice, apacket, etc. transmitted to each UE and includes a physical uplinkshared channel (PUSCH). A control region refers to a communicationresource for transmission of an uplink control signal, for example,downlink channel quality report from each UE, reception ACK/NACK for adownlink signal, uplink scheduling request, etc. and includes a physicaluplink control channel (PUCCH). A sounding reference signal (SRS) istransmitted through an SC-FDMA symbol that is lastly positioned in thetime axis in one subframe. SRSs of a plurality of UEs, which aretransmitted to the last SC-FDMAs of the same subframe, can bedifferentiated according to frequency positions/sequences. The SRS isused to transmit an uplink channel state to an eNB and is periodicallytransmitted according to a subframe period/offset set by a higher layer(e.g., RRC layer) or aperiodically transmitted at the request of theeNB.

Next, HARQ (Hybrid Automatic Repeat reQuest) will be described. When aplurality of UEs has data to be transmitted on uplink/downlink in awireless communication, an eNB selects UEs which will transmit data pertransmission time internal (TTI) (e.g., subframe). In a system usingmultiple carriers and the like, an eNB selects UEs which will transmitdata on uplink/downlink per TTI and also selects a frequency band to beused for data transmission of the corresponding UEs.

When description is based on uplink (UL), UEs transmit reference signals(or pilot signals) on uplink and an eNB detects channel states of theUEs using the reference signals transmitted from the UEs and selects UEswhich will transmit data on uplink in each unit frequency band per TTI.The eNB notifies the UEs of the result of selection. That is, the eNBtransmits, to UL scheduled UEs, a UL assignment message indicating thatthe UEs may transmit data using a specific frequency band in a specificTTI. The UL assignment message is also referred to as a UL grant. TheUEs transmit data on uplink according to the UL assignment message. TheUL assignment message may include UE identity (ID), RB allocationinformation, a modulation and coding scheme (MCS), a redundancy version(RV), new data indication (NDI) and the like.

In the case of a synchronous non-adaptive HARQ method, a retransmissiontime is appointed in the system (e.g., after 4 subframes from a NACKreception time). Accordingly, the eNB may send a UL grant message to UEsonly in initial transmission and subsequent retransmission is performedaccording to an ACK/NACK signal (e.g., PHICH signal). On the other hand,in the case of an asynchronous adaptive HARQ method, a retransmissiontime is not appointed and thus the eNB needs to send a retransmissionrequest message to UEs. Further, the retransmission request message mayinclude UE ID, RB allocation information, HARQ process ID/number. RV andNDI information because frequency resources or an MCS for retransmissionvary with transmission time.

FIG. 7 illustrates a UL HARQ operation in an LTE (-A) system. In the LTE(-A) system, the asynchronous adaptive HARQ method is used as a UL HARQmethod. When 8-channel HARQ is used, 0 to 7 are provided as HARQ processnumbers. One HARQ process operates per TTI (e.g., subframe). Referringto FIG. 7, a UL grant is transmitted to a UE 120 through a PDCCH (S600).The UE 120 transmits UL data to an eNB 110 after 4 subframes from thetime (e.g., subframe 0) at which the UL grant is received using an RBand an MCS designated by the UL grant (S602). The eNB 110 decodes the ULdata received from the UE 120 and then generates ACK/NACK. When decodingof the UL data fails, the eNB 110 transmits NACK to the UE 120 (S604).The UE 120 retransmits the UL data after 4 subframes from the time atwhich NACK is received (S606). Initial transmission and retransmissionof the UL data are performed through the same HARQ process (e.g., HARQprocess 4). ACK/NACK information may be transmitted through a PHICH.

With respect to TDD cells, the following problem may be generated when aUE transmits an ACK/NACK signal to a base station. When the UE missessome of PDCCHs transmitted by the base station for a period of aplurality of subframes, the UE cannot be aware of the fact that PDSCHscorresponding to the missed PDCCHs have been transmitted thereto andthus an error may be generated in generation of ACK/NACK.

To solve this, a DL grant PDCCH/SPS release PDCCH for TDD cells includesa DAI field (i.e., DL DAI field). The value of the DL DAI fieldindicates a cumulative value (i.e., counting value) of PDCCHscorresponding to PDSCHs and PDCCHs indicating downlink SPS release up tothe current subframe in n−k (k⊂K) DL subframes corresponding to a ULsubframe carrying ACK/NACK. The in n−k (k⊂K) DL subframes refer to DLsubframes corresponding to a UL subframe carrying ACK/NACK. For example,when three DL subframes correspond to a single UL subframe, PDSCHstransmitted in the period of the three DL subframes are sequentiallyindexed (i.e., sequentially counted) and transmitted in a PDCCH whichschedules the PDSCHs. The UE can recognize whether a previous PDCCH hasbeen successfully received through DAI information included in thePDCCH.

FIG. 8 illustrates ACK/NACK transmission using a DL DAI. This example isbased on the assumption that a TDD system has a configuration of 3 DLsubframes: 1 UL subframe. It is assumed that a UE transmits ACK/NACKusing a PUSCH resource for convenience. When ACK/NACK is transmittedthrough a PUSCH in LTE, 1-bit or 2-bit bundled ACK/NACK is transmitted.

Referring to FIG. 8, when the second PDCCH is missed as in the firstexample (EX 1), the UE can recognize that the second PDCCH is missedbecause the DL DAI value of the third PDCCH differs from the number ofPDCCHs detected so far. In this case, the UE may process an ACK/NACKresponse to the second PDCCH as NACK (or NACK/DTX). When the last PDCCHis missed as in the second example (EX 2), the UE may not know that thelast PDCCH is missed because the DAI value of the finally detected PDDCHcorresponds to the number of PDCCHs detected so far (i.e., DTX).Accordingly, the UE recognizes that only two PDCCHs have been scheduledfor the DL subframe period. In this case, the UE bundles only ACK/NACKcorresponding to the first two PDCCHs, causing generation of an error inan ACK/NACK feedback procedure. To solve this, a UL grant PDCCH alsoincludes a DAI field (i.e., UL DAI field). The UL DAI field is a 2-bitfield and indicates information about the number of scheduled PDCCHs.

FIG. 9 illustrates carrier aggregation (CA) communication system.

Referring to FIG. 9, a plurality of UL/DL component carriers (CCs) canbe aggregated to support a wider UL/DL bandwidth. The CCs may becontiguous or non-contiguous in the frequency domain. Bandwidths of theCCs can be independently determined. Asymmetrical CA in which the numberof UL CCs is different from the number of DL CCs can be implemented.Control information may be transmitted/received only through a specificCC. This specific CC may be referred to as a primary CC and other CCsmay be referred to as secondary CCs. For example, when cross-carrierscheduling (or cross-CC scheduling) is applied, a PDCCH for downlinkallocation can be transmitted on DL CC #0 and a PDSCH correspondingthereto can be transmitted on DL CC #2. The term “component carrier” maybe replaced by other equivalent terms (e.g. “carrier”, “cell”, etc.).

For cross-CC scheduling, a carrier indicator field (CIF) is used.Presence or absence of the CIF in a PDCCH can be determined by higherlayer signaling (e.g. RRC signaling) semi-statically and UE-specifically(or UE group-specifically). The baseline of PDCCH transmission issummarized as follows.

▪ CIF disabled: a PDCCH on a DL CC is used to allocate a PDSCH resourceon the same DL CC or a PUSCH resource on a linked UL CC.

● No CIF

▪ CIF enabled: a PDCCH on a DL CC can be used to allocate a PDSCH orPUSCH resource on a specific DL/UL CC from among a plurality ofaggregated DL/UL CCs using the CIF.

● LTE DCI format extended to have CIF

CIF corresponds to a fixed x-bit field (e.g. x=3) (when CIF is set)

CIF position is fixed irrespective of DIC format size (when CIF is set)

When the CIF is present, the BS may allocate a monitoring DL CC (set) toreduce BD complexity of the UE. For PDSCH/PUSCH scheduling, the UE maydetect/decode a PDCCH only on the corresponding DL CCs. The BS maytransmit the PDCCH only through the monitoring DL CC (set). Themonitoring DL CC set may be set UE-specifically, UE-group-specificallyor cell-specifically.

FIG. 10 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isset to a PDCCH CC. DL CC A˜C may be referred to as a serving CC, servingcarrier, serving cell, etc. When the CIF is disabled, each DL CC cantransmit only a PDCCH that schedules a PDSCH corresponding to the DL CCwithout a CIF according to LTE PDCCH rule (non-cross-CC scheduling).When the CIF is enabled through UE-specific (or UE-group-specific orcell-specific) higher layer signaling, a specific CC (e.g. DL CC A) cantransmit not only the PDCCH that schedules the PDSCH of DL CC A but alsoPDCCHs that schedule PDSCHs of other DL CCs using the CIF(cross-scheduling). A PDCCH is not transmitted on DL CC B and DL CC C.

As more and more telecommunication devices require greater communicationcapacity, efficient utilization of limited frequency bands in futurewireless communication systems is increasingly important. Basically, thefrequency spectrum is divided into a licensed band and an unlicensedband. The licensed band includes frequency bands reserved for specificuses. For example, the licensed band includes government allocatedfrequency bands for cellular communication (e.g., LTE frequency bands).The unlicensed band is a frequency band reserved for public use and isalso referred to as a license-free band. The unlicensed band may be usedby anyone without permission or declaration so long as such use meetsradio regulations. The unlicensed band is distributed or designated foruse by anyone at a close distance, such as within a specific area orbuilding, in an output range that does not interfere with thecommunication of other wireless stations, and is widely used forwireless remote control, wireless power transmission, Wi-Fi, and thelike.

Cellular communication systems such as LTE systems are also exploringways to utilize unlicensed bands (e.g., the 2.4 GHz band and the 5 GHzband), used in legacy Wi-Fi systems, for traffic off-loading. Basically,since it is assumed that wireless transmission and reception isperformed through contention between communication nodes, it is requiredthat each communication node perform channel sensing (CS) beforetransmitting a signal and confirm that none of the other communicationnodes transmit a signal. This operation is referred to as clear channelassessment (CCA), and an eNB or a UE of the LTE system may also need toperform CCA for signal transmission in an unlicensed band. Forsimplicity, the unlicensed band used in the LTE-A system is referred toas the LTE-U band. In addition, when an eNB or UE of the LTE systemtransmits a signal, other communication nodes such as Wi-Fi should alsoperform CCA in order not to cause interference. For example, in the801.11ac Wi-Fi standard, the CCA threshold is specified to be −62 dBmfor non-Wi-Fi signals and −82 dBm for Wi-Fi signals. Accordingly, thestation (STA)/access point (AP) does not perform signal transmission soas not to cause interference when a signal other than Wi-Fi signals arereceived at a power greater than or equal to −62 dBm. In a Wi-Fi system,the STA or AP may perform CCA and signal transmission if a signal abovea CCA threshold is not detected for more than 4 μs.

FIG. 11 illustrates carrier aggregation of a licensed band and anunlicensed band. Referring to FIG. 11, an eNB may transmit a signal to aUE or the UE may transmit a signal to the eNB in a situation of carrieraggregation of the licensed band (hereinafter, LTE-A band, L-band) andthe unlicensed band (hereinafter, LTE-U band, U-band). Here, the centercarrier or frequency resource of the license band may be interpreted asa PCC or PCell, and the center carrier or frequency resource of theunlicensed band may be interpreted as an SCC or SCell.

FIGS. 12 and 13 illustrate a method of occupying resources within alicensed band. In order to perform communication between an eNB and a UEin an LTE-U band, the band should be occupied/secured for a specifictime period through contention with other communication systems (e.g.,Wi-Fi) unrelated to LTE-A. For simplicity, the time periodoccupied/secured for cellular communication in the LTE-U band isreferred to as a reserved resource period (RRP). There are variousmethods for securing the RRP interval. For example, a specificreservation signal may be transmitted such that other communicationsystem devices such as Wi-Fi can recognize that the correspondingwireless channel is busy. For example, the eNB may continuously transmitan RS and data signal such that a signal having a specific power levelor higher is continuously transmitted during the RRP interval. If theeNB has predetermined the RRP interval to occupy in the LTE-U band, theeNB may pre-inform the UE of the RRP interval to allow the UE tomaintain the communication transmission/reception link during theindicated RRP interval. The RRP interval information may be transmittedto the UE through another CC (e.g., the LTE-A band) connected throughcarrier aggregation.

For example, an RRP interval consisting of M consecutive subframes (SF)may be configured. Alternatively, one RRP interval may be configured asa set of non-consecutive SFs (not shown). Here, the eNB may pre-informthe UE through higher layer signaling (e.g., RRC or MAC signaling) or aphysical control/data channel of the value of M and the usage of the MSFs (using PCell). The start time of the RRP interval may be setperiodically by higher layer signaling (e.g., RRC or MAC signaling).Alternatively, the start time of the RRP interval may be specifiedthrough physical layer signaling (e.g., (E)PDCCH) in SF #n or SF # (n-k)when the start time of the RRP interval needs to be set to SF #n. Here,k is a positive integer (e.g., 4).

The RRP may be configured such that the SF boundary and the SFnumber/index thereof are aligned with the PCell (FIG. 2) (hereinafter,“aligned-RRP”), or configured to support the format in which the SFboundary or the SF number/index is not aligned with the PCell(hereinafter, “floating-RRP”) (FIG. 13). In the present invention, theSF boundaries being aligned between cells may mean that the intervalbetween SF boundaries of two different cells is shorter than or equal toa specific time (e.g., CP length or X μs (X≥0)). In addition, in thepresent invention, a PCell may refer to a cell that is referenced inorder to determine the SF (and/or symbol) boundary of a UCell in termsof time (and/or frequency) synchronization.

As another example of operation in the unlicensed band performed in acontention-based random access scheme, the eNB may perform carriersensing before data transmission/reception. If a current channel statusof the SCell is determined as being an idle when the channel status ischecked for whether it is busy or idle, the eNB may transmit ascheduling grant (e.g., (E)PDCCH) through the PCell (LTE-A band) or theSCell (LTE-U band), and attempt to perform data transmission/receptionon the SCell. For convenience, a serving cell (e.g., PCell and SCell)operating in a licensed band is defined as LCell and a center frequencyof the LCell is defined as (DL/UL) LCC. A serving cell (e.g., SCell)operating in an unlicensed band is defined as UCell and a centerfrequency of the UCell is defined as (DL/UL) UCC. In addition, a case inwhich a UCell is scheduled from the same cell and a case in which aUCell is scheduled from a different cell (e.g., PCell) are respectivelyreferred to as self-CC scheduling and cross-CC scheduling.

Embodiment: Signal Transmission and Reception in LTE LAA (LicensedAssisted Access)

In LTE-A, CA for a plurality of serving cells (i.e., cells) may be setfor one UE, and UL control signaling (e.g., a PUCCH) carrying HARQ-ACKfeedback for DL data (e.g., a PDSCH) transmission scheduled in theplurality of cells may be performed only through a PCell. In addition,to reduce UL control resource burden due to intensive PUCCH transmissionin a PCell (in a manner of offloading to other cells, for example) andto support simultaneous access to cell groups (e.g., CGs)controlled/managed by different base stations, that is, setting of DC(Dual Connectivity) for one UE, systems may be configured such thatPUCCH transmission can be performed through a specific SCell instead ofa PCell in systems following LTE-A.

Distinguished from cells (i.e., LCells) on conventional licensed bandsin which DL/UL resources are always consecutively or periodicallyconfigured, DL/UL resources are aperiodically or opportunisticallyconfigured depending on a CCA result with respect to a UCell radiochannel between a base station and a UE in cells (i.e., UCells) onunlicensed bands. CCA results are divided into CCA success/failure. ACCA result corresponds to CCA success when a channel sensing resultindicates that a channel is idle and corresponds to CCA failure when thechannel sensing result indicates that the channel is busy. Accordingly,whether DL scheduling with respect to a UCell is possible is determinedaccording to CCA success/failure of the base station for a UCell radiochannel, and transmission of UL data (e.g., a PUSCH) scheduled in theUCell is also determined according to CCA success/failure of the UE forthe UCell radio channel.

In future systems, PUCCH offloading to a UCell and/or setting of DC witha cell group (CG) composed of only UCells may be considered. To thisend, an operation of enabling transmission of a PUCCH carrying UCI suchas HARQ-ACK (i.e., A/N) through the UCell may be required. However,whether to perform UL transmission such as PUSCH transmission throughthe UCell depends on CCA success/failure of the UE for the UCell andthis restriction may be also imposed on PUCCH transmission. For example,to transmit an A/N PUCCH for PDSCH reception through the UCell, the UEmay perform CCA for the UCell. The UE may transmit the PUCCH to theUCell when the CCA result is CCA success and drop PUCCH transmissionwhen the CCA result is CCA failure.

In a situation of A/N PUCCH transmission on the UCell, the base stationperforms DTX detection for PUCCH transmission of the UE to predict CCAfailure in the UE and may perform an appropriate operation (e.g.,retransmission PDSCH scheduling) according thereto. However, 1) aDTX-to-ACK error may cause RLC (Radio Link Control) level retransmissionto considerably increase latency when PUCCH DTX detection performance inthe base station is not secured, 2) ACK-to-DTX error may causeunnecessary PDSCH retransmission (and DL grant PDCCH transmission forscheduling thereof) even if PUCCH DTX detection performance is secured,or 3) NACK-to-DTX error may cause unnecessary DCI overhead increase(because the base station erroneously predicts the cause of PUCCH DTX asDL grant PDCCH detection failure instead of CCA failure of the UE).

To solve this, a method of providing multiple PUCCH transmissionopportunities for the same A/N information in the case of the UCell(distinguished from the conventional LCell) may be considered. That is,the UE may be configured to perform multiple CCA procedures for A/NPUCCH transmission. However, A/N transmission timings for PDSCHreceptions in different DL SFs may overlap in the same UL SF (accordingto a CCA result of the UE for each UL SF) and thus inconsistency in A/Npayload configuration may occur between the UE and the base station(i.e., which A/N information corresponds to which DL SF is ambiguous).For example, when the UE is configured to respectively perform A/Ntransmissions for PDSCH receptions in DL SF #n and DL SF #(n+1) throughUL SF #(n+K) and UL SF #(n+K+1), if the UE fails in CCA with respect toUL SF #(n+K) and succeeds in CCA with respect to UL SF #(n+K+1), whichone of A/N signals for DL SF #n and DL SF #(n+1) will be transmittedthrough UL SF #(n+K+1) may be ambiguous.

The present invention proposes effective methods of transmitting a UCIPUCCH on a UCell which are able to prevent inconsistency in A/N payloadconfiguration while providing multiple PUCCH transmission (multiple CCAprocedures therefor) opportunities. Prior to description, it is assumedthat an A/N PUCCH corresponding to PDSCH reception in DL SF #n istransmitted through UL SF #(n+K) in an ideal situation having no CCAfailure (e.g., K=4) and DL SF #n corresponds to UL SF #(n+K). In thepresent invention, DL grant DCI for scheduling PUCCH transmission in SF#(n+K) and PDSCH transmission in SF #n corresponding thereto may bereplaced by UL grant DCI for scheduling PUSCH transmission in SF #(n+K)and the corresponding PUSCH.

In the present invention, a PUCCH payload transmitted through one UL SFmay be composed of multiple A/Ns for an SF group (composed of multipleSFs) including a DL SF corresponding to the UL SF and previous SFs. Thefollowing A/N transmission methods may be considered according tomethods of configuring an SF group (and configuring an A/N payloadaccording thereto).

(1) Method 1: SF Number Based A/N Payload Configuration (SF Group BasedA/N)

In this method, a plurality of A/Ns for an SF group composed of aplurality of SFs having consecutive SF numbers may be configured as anA/N payload on one PUCCH. Accordingly, an SF group corresponding to A/NPUCCH transmission in a UL SF may be composed of a DL SF correspondingto the UL SF and previous consecutive SFs. Specifically, (when PDSCHtransmission in SF #n is scheduled) an A/N payload transmitted throughUL SF #(n+K) may be composed of A/N for an SF group composed of L SFs ofSF #(n−L+1) to SF #n. The value L (and/or K, which are SF group starttime related information) corresponding to the SF group size may bepreset through higher layer signaling such as RRC signaling or directlyindicated through DL grant DCI (which schedules PDSCH transmission in SF#n, for example).

For example, if the UE fails in CCA for UL SF #(n+K) on the UCell in astate in which PDSCH transmission in SF #n is scheduled, the UE may begiven multiple opportunities to perform CCA for M UL SFs including UL SF#(n+K) and permitted to perform A/N PUCCH transmission according to theCCA result. The value M corresponds to the (maximum) number of CCA orPUCCH transmission opportunities and may be preset through higher layersignaling such as RRC signaling or directly indicated through DL grantDCI (which schedules PDSCH transmission in SF #n, for example). Based onthis, the UE may 1) perform A/N PUCCH transmission only through a UL SFin which CCA has been initially successfully performed among the M ULSFs or 2) perform A/N PUCCH transmission through all UL SFs in which CCAhas been successfully performed among the M UL SFs. When CCA for UL SF#(n+K) has failed and then CCA for UL SF #(n+K+m) has been successfullyperformed, A/N for L SFs shifted by m SFs in the SF group correspondingto UL SF #(n+K), that is, SF #((n+m)−(L+1)) to SF #(n+m) may betransmitted through the PUCCH in UL SF #(n+K+m).

Alternatively, the UE may operate to transmit A/N for an SF groupcorresponding to a UL SF through a PUCCH/PUSCH in all UL SFs all thetime irrespective of PDSCH reception/scheduling in an SF (e.g., SF #ncorresponding to UL SF #(n+K)) corresponding to the UL SF in whichPUCCH/PUSCH transmission is performed. Alternatively, only when PDSCHreception/scheduling is present in an SF (e.g., SF #n corresponding toUL SF #(n+K)) corresponding to a UL SF in which PUCCH/PUSCH transmissionis performed, the UE may transmit A/N for an SF group corresponding tothe UL SF through the PUCCH/PUSCH. Alternatively, only when PDSCHreception/scheduling is present in an SF group (e.g., L SFs of SF#(n−L+1) to SF #n corresponding to UL SF #(n+K)) corresponding to a ULSF in which PUCCH/PUSCH transmission is performed, the UE may transmitA/N for the SF group through the PUCCH/PUSCH. Here, “when PDSCHreception/scheduling is present” may be limited to cases in which thereis to-be-newly-transmitted A/N of a specific number of bits (e.g., X) ormore or a specific % (e.g., Y %) or more in a maximum A/N payload (e.g.,a total number of A/N bits when SF group based A/N is configured for allcells). X and Y are positive numbers (e.g., integers).

Alternatively, whether to transmit A/N for an SF group corresponding toa UL SF in which PUSCH transmission is performed through thecorresponding PUSCH may be directly indicated through a UL grant whichschedules PUSCH transmission. For example, in a state in which aplurality of cell groups has been configured through higher layersignaling (e.g., RRC signaling), a cell group (PDSCH scheduling therein)for which SF group based A/N will be transmitted through a PUSCH amongthe plurality of cell groups may be indicated through a UL grant. In thecase of a multi-SF scheduling method for simultaneously schedulingmultiple PUSCH transmissions in multiple SFs through single UL grant DCItransmission, indication of whether to transmit A/N may be provided perPUSCH transmission in each SF or only one indication with respect towhether to transmit A/N may be provided for PUSCH transmission in allSFs. In the latter case, one A/N transmission indication may be 1)applied to all scheduled PUSCH transmissions, 2) applied only to theinitially scheduled/transmitted PUSCH or 3) applied only to theinitially scheduled/transmitted PUSCH in an SF groups having consecutiveSFs when scheduled SFs are not consecutive.

For example, if the UE fails in CCA for UL SF #(n+K) on the UCell in astate in which transmission of a PUSCH including A/N has been scheduledin UL SF #(n+K), the UE may be given multiple opportunities to performCCA for UL SF #(n+K) and following M UL SF and permitted to performPUSCH transmission according to the CCA result. Here, the value Mcorresponds to the (maximum) number of CCA or PUSCH transmissionopportunities and may be preset through higher layer signaling such asRRC signaling or directly indicated through UL grant DCI (whichschedules PUSCH transmission in SF #(n+K), for example). Based on this,the UE may 1) perform PUSCH transmission only through a UL SF in whichCCA has been initially successfully performed among the M UL SFs or 2)perform PUSCH transmission through all UL SFs in which CCA has beensuccessfully performed among the M UL SFs. When CCA for UL SF #(n+K) hasfailed and then CCA for UL SF #(n+K+m) has been successfully performed,A/N for L SFs shifted by m SFs in the SF group corresponding to UL SF#(n+K), that is, SF #((n+m)−(L+1)) to SF #(n+m) may be transmittedthrough the PUSCH in UL SF #(n+K+m).

FIG. 14 illustrates an A/N transmission method when L=4 and K=4.Referring to FIG. 14, when CCA for UL SF #(n+K) has been successfullyperformed, a UE may transmit A/N for SF #(n−4+1) to SF #n in SF #(n+K).If CCA for UL SF #(n+K) has failed and then CCA for UL SF #(n+K+1) hasbeen successfully performed, the UE may transmit A/N for SF#((n+1)−(4+1) to SF #(n+1) in SF #(n+K+1). A/N may be transmittedthrough a PUCCH or a PUSCH.

For more flexible DL/UL resource configuration and operation/managementon UCells, a method of directly indicating an A/N transmission timingcorresponding to PDSCH reception through DL grant DCI may be considered.Specifically, when a minimum delay between a PDSCH and A/N is assumed tobe Dm SFs (e.g., Dm=4) and an A/N delay value indicated through DL grantDCI is assumed to be Dg (e.g., Dg=0, 1, . . . ), a time corresponding to(Dm+Dg) SFs may be determined as an actual delay between the PDSCH andthe A/N. When the number of A/N delay values of Dg is assumed to be Nd(e.g., Dg=0, 1, . . . , Nd−1), an A/N payload (codebook) transmittedthrough a PUCCH/PUSCH in SF #N may be composed of A/N responses to PDSCHreceptions in Nd SFs corresponding to SF #(N−Dm−Dg). In this case,Method 1 may be applied with Nd and Dm replaced by L and M respectively(here, M=1 or M>1), and the SF group size L may be set to a valuegreater than the number of A/N delay values, Nd, in order to providemultiple PUCCH transmission (multiple CCA procedures therefor)opportunities for A/N corresponding to one PDSCH.

If the UE is aware of actual DL/UL SF configuration information on aUCell through specific signaling, the number of DL SFs (i.e., A/Npayload size) corresponding to an actual A/N feedback target (except ULSFs or a period having no SF configuration) may be set differently perUL SF in which A/N transmission is performed within a corresponding SFgroup. Here, specific signaling may be UE-common signaling (SF-configDCI) (e.g., PDCCH) transmitted through a DL SF (e.g., a PDCCH commonsearch space on the DL SF) on the UCell. For example, in a state inwhich the SF group size L is given, 1) an A/N payload may be configuredonly for SFs corresponding to DL among L consecutive SFs (before aspecific time) on the basis of the specific time (prior to an A/Ntransmission SF) without discriminating DL SF from UL SF or 2) an A/Npayload may be configured for L sequential DL SFs (before a specifictime) on the basis of the specific time (prior to an A/N transmissionSF) irrespective of whether the DL SFs are consecutive.

In addition, the number of A/N PUCCH transmission opportunities may beset per DL SF scheduled for the UE according to DL/UL SF configurationon the UCell. For example, in a state in which the number of PUCCHtransmission opportunities, M, is given, 1) PUCCH transmission may beperformed only through SFs corresponding to UL among M consecutive SFs(after a specific time) on the basis of the specific time (after an A/Ntransmission SF) without discriminating DL SF from UL SF or 2) A/Ntransmission (corresponding to a relevant DL SF) may be performedthrough M sequential UL SFs (after a specific time) on the basis of thespecific time (after a scheduled DL SF) irrespective of whether the ULSFs are consecutive.

In the present method, multiple A/Ns for multiple SFs are transmittedthrough a single PUCCH, and thus a larger UCI payload size and a largeramount of UL control resources may be required compared to a PUCCHcarrying a single A/N. To reduce such overhead, an A/N payload in UL SF#(n+K) may be configured using only a single A/N for SF #n (instead ofmultiple A/Ns for an entire SF group) when an SF group corresponding toUL SF #(n+K) includes only one SF in which a PDSCH scheduled, SF #n(which is referred to as single SF A/N). Accordingly, when a PDSCH isscheduled in SFs other than SF #n, an A/N payload may be composed ofmultiple A/Ns for an SF group of SF #(n−L+1) to SF #n (which is referredto as SF group A/N). PUCCH formats (and/or the numbers of resources)used for single SF A/N and SF group A/N may be set/allocateddifferently.

In the case of Method 1, A/N transmission opportunity for a DL SF whichis not included in an SF group may be lost when the SF group sizedecreases and the UE frequently fails in CCA (continuously) due tocharacteristics of an operation of transmitting A/N for an SF groupshifted in time. To alleviate this phenomenon, an A/N payload may beconfigured on the basis of a HARQ process ID (Method 2) or an A/Npayload may be configured on the basis of a DAI in DL grant DCI (Method3).

(2) Method 2: HARQ Process ID Based A/N Payload Configuration (HARQProcess ID Based A/N)

In this method, a plurality of A/Ns corresponding to all HARQ processIDs may be configured as an A/N payload on one PUCCH. Specifically, ifthere are N HARQ process IDs of 0 to (N−1), a plurality of A/Nscorresponding to the N HARQ process IDs may be transmitted through onePUCCH. Alternatively, all HARQ process IDs may be divided into aplurality of ID groups (through higher layer signaling such as RRCsignaling) in advance and then A/N to be transmitted which correspondsto one of the plurality of ID groups may be indicated through DL grantDCI. In this case. HARQ process IDs may be configured such that one HARQprocess ID (commonly) belongs to one or more ID groups. Further, one ofthe plurality of ID groups may include all HARQ process IDs. When aplurality of A/Ns for PDSCHs having different reception timings ispresent for the same HARQ process ID, A/N for the most recently receivedPDSCH may be determined as A/N corresponding to the HARQ process ID.

When PDSCH transmission is scheduled in SF #n, for example, as in Method1, in this method, multiple CCA execution opportunities may be given forUL SF #(n+K) corresponding to SF #n and following M UL SF and anoperation of performing A/N PUCCH transmission may be allowed accordingto the CCA result. Here, the value M corresponds to the (maximum) numberof CCA execution or PUCCH transmission opportunities and may beset/indicated through higher layer signaling such as RRC signaling or DLgrant DCI. A UE 1) may perform A/N PUCCH transmission only through a ULSF in which CCA has been initially successfully performed among the M ULSFs or 2) may perform A/N PUCCH transmission through all UL SFs in whichCCA has been successfully performed among the M UL SFs. Accordingly, A/Ninformation corresponding to the same HARQ process ID may be transmittedthrough a plurality of PUCCHs multiple times. Here, A/N informationcorresponding to each HARQ process ID may be reset/repeated per PUCCHtransmission. Whether resetting/repetition is performed may be set by aBS or determined according to intervals of UL SFs in which A/N PUCCHtransmission is performed. For example, when the intervals of the UL SFsare less than a reference value (e.g., P SFs), A/N informationcorresponding to each HARQ process ID may be repeated per PUCCHtransmission. When the intervals of the UL SFs are greater than thereference value (e.g., P SFs), A/N information corresponding to eachHARQ process ID may be reset per PUCCH transmission. P corresponds tothe number of HARQ process IDs or a multiple thereof.

A case in which A/N information corresponding to each HARQ process ID isreset per PUCCH transmission is described. For example, when a decodingresult with respect to PDSCH reception (HARQ process ID=0) in SF #n isACK, A/N information corresponding to HARQ process ID=0 may be mapped asACK only to a payload of a PUCCH initially transmitted after UL SF#(n+K) including UL SF #(n+K) and A/N information corresponding to HARQprocess ID=0 may be reset in a payload of a PUCCH transmitted followingthe initially transmitted PUCCH. When a decoding result with respect toPDSCH reception (HARQ process ID=0) in SF #n is NACK (or DTX), A/Ninformation corresponding to HARQ process ID=0 may be mapped as NACK (orDTX) to a payload of a PUCCH initially transmitted after UL SF #(n+K)including UL SF #(n+K) and A/N information corresponding to HARQ processID=0 may be updated according to a retransmission data decoding resultin a payload of the PUCCH transmitted following the initiallytransmitted PUCCH. When there is no new transmission (e.g., PDSCHtransmission) corresponding to HARQ process ID=0 after A/N informationcorresponding to HARQ process ID=0 is reset, the A/N informationcorresponding to HARQ process ID=0 may be mapped as DTX (or NACK). Onthe contrary, when there is a new transmission (e.g., PDSCHtransmission) corresponding to HARQ process ID=0 after the A/Ninformation corresponding to HARQ process ID=0 is reset, the A/Ninformation corresponding to HARQ process ID=0 may be mapped to adecoding result with respect to the new transmission (e.g., PDSCHtransmission).

Alternatively, the UE may operate to always transmit A/N for (all) HARQprocess IDs (groups) through a PUCCH/PUSCH in all UL SFs irrespective ofPDSCH reception/scheduling in an SF corresponding to a UL SF in whichPUCCH/PUSCH transmission is performed (e.g., SF #n corresponding to ULSF #(n+K)). Alternatively, the UE may transmit A/N for (all) HARQprocess IDs (groups) through a PUCCH/PUSCH only when PDSCHreception/scheduling exists in an SF corresponding to a UL SF in whichPUCCH/PUSCH transmission is performed (e.g., SF #n corresponding to ULSF #(n+K)). Alternatively, the UE may transmit A/N for (all) HARQprocess IDs (groups) through a PUCCH/PUSCH only when PDSCHreception/scheduling exists in an SF group corresponding to a UL SF inwhich PUCCH/PUSCH transmission is performed (e.g., L SFs of SF #(n−L+1)to SF #n corresponding to UL SF #(n+K)). Here, “when PDSCHreception/scheduling exists” may be limited to cases in which there isA/N corresponding to a specific number of bits (e.g., X) or more orspecific % (e.g., Y %) or more which will be newly transmitted in amaximum A/N payload (e.g., a total number of A/N bits when HARQ processID based A/N is configured for all cells). X and Y are positive numbers(e.g., integers).

Alternatively, it is possible to indicate whether A/N for (all) HARQprocess IDs (groups) is transmitted through a PUSCH through a UL grantwhich schedules PUSCH transmission or a DL grant which schedules PDSCHtransmission. For example, in a state in which a plurality of cellgroups has been set through higher layer signaling (e.g., RRC signaling)in advance, a cell group (PDSCH scheduling therein) for which HARQprocess ID based A/N will be transmitted through a PUSCH may beindicated through a UL grant/DL grant. In the case of multi-SFscheduling method in which multiple PUSCH transmissions in multiple SFsare simultaneously scheduled through single UL grant DCI transmission,whether A/N is transmitted may be individually indicated per PUSCHtransmission in each SF or whether A/N is transmitted may be indicatedonce for PUSCH transmission in all SFs. In the latter case, oneindication of whether A/N is transmitted 1) may be applied to allscheduled PUSCH transmissions, 2) may be applied to only an initiallyscheduled/transmitted PUSCH or 3) may be applied to an initiallyscheduled/transmitted PUSCH in a group of consecutive SFs when scheduledSFs are not consecutive.

When transmission of a PUSCH including A/N is scheduled in UL SF #(n+K)as in Method 1, in this method, the UE is given multiple CCA executionopportunities for UL SF #(n+K) and following M UL SF and may be allowedto perform an operation of performing PUSCH transmission according tothe CCA result. Here, the value M corresponds to the (maximum) number ofCCA execution or PUSCH transmission opportunities and may be previouslyset through higher layer signaling such as RRC signaling or indicatedthrough UL grant DCI (which schedules PUSCH transmission in UL SF#(n+K), for example). The UE 1) may perform transmission of the PUSCH(including A/N) only through a UL SF in which CCA has been initiallysuccessfully performed among the M UL SFs or 2) may perform transmissionof the PUSCH (including A/N) through all UL SFs in which CCA has beensuccessfully performed among the M UL SFs. Accordingly, A/N informationcorresponding to the same HARQ process ID may be transmitted through aplurality of PUSCHs multiple times. Here, A/N information correspondingto each HARQ process ID may be reset/repeated per PUSCH transmission.Whether resetting/repetition is performed may be set by a BS ordetermined according to intervals of UL SFs in which A/N PUSCHtransmission is performed. For example, when the intervals of the UL SFsare less than a reference value (e.g., P SFs), A/N informationcorresponding to each HARQ process ID may be repeated per PUSCHtransmission. When the intervals of the UL SFs are greater than thereference value (e.g., P SFs), A/N information corresponding to eachHARQ process ID may be reset per PUSCH transmission. P corresponds tothe number of HARQ process IDs or a multiple thereof.

A case in which A/N information corresponding to each HARQ process ID isreset per PUSCH transmission is described. For example, when a decodingresult with respect to PDSCH reception (HARQ process ID=0) in SF #n isACK, A/N information corresponding to HARQ process ID=0 may be mapped asACK only to a payload of a PUSCH initially transmitted after UL SF#(n+K) including UL SF #(n+K) and A/N information corresponding to HARQprocess ID=0 may be reset in a payload of a PUSCH transmitted followingthe initially transmitted PUCCH. When a decoding result with respect toPDSCH reception (HARQ process ID=0) in SF #n is NACK (or DTX), A/Ninformation corresponding to HARQ process ID=0 may be mapped as NACK (orDTX) to a payload of a PUSCH initially transmitted after UL SF #(n+K)including UL SF #(n+K) and A/N information corresponding to HARQ processID=0 may be updated according to a retransmission data decoding resultin a payload of the PUSCH transmitted following the initiallytransmitted PUSCH. When there is no new transmission (e.g., PDSCHtransmission) corresponding to HARQ process ID=0 after A/N informationcorresponding to HARQ process ID=0 is reset, the A/N informationcorresponding to HARQ process ID=0 may be mapped as DTX (or NACK). Onthe contrary, when there is a new transmission (e.g., PDSCHtransmission) corresponding to HARQ process ID=0 after the A/Ninformation corresponding to HARQ process ID=0 is reset, the A/Ninformation corresponding to HARQ process ID=0 may be mapped to adecoding result with respect to the new transmission (e.g., PDSCHtransmission).

In this method, a plurality of A/Ns corresponding to a plurality of HARQprocess IDs is transmitted through one PUCCH and thus a relatively largeUCI payload size and a large amount of UL control resources may beneeded. In consideration of this, when there is only one HARQ process IDscheduled through SF #n as an actually scheduled HARQ process ID(corresponding to a case in which a PDSCH signal exists in a receptionbuffer) among all HARQ process IDs, an A/N payload in UL SF #(n+K) maybe composed of only a single A/N for SF #n (instead of a plurality ofA/Ns for all HARQ process IDs) (referred to as “single ID A/N”hereinafter). Accordingly, when a PDSCH is scheduled for SFs other thanSF #n (or HARQ process IDs other than the HARQ process ID scheduled inSF #n), an A/N payload may be composed of a plurality of A/Ns for allHARQ process IDs (referred to as “all ID A/N” hereinafter). PUCCHformats (and/or the number of resources) used in single ID A/N and allID A/N may be differently set/allocated.

Furthermore, an A/N payload configuration method combined with the SFgroup concept of Method I is possible. Accordingly, A/N corresponding toa HARQ process ID may be configured only for PDSCH scheduling in aspecific SF group. For example, an A/N payload in UL SF #(n+K) may becomposed of A/N corresponding to a HARQ process ID only on the basis ofPDSCH scheduling in a group of SFs of SF #(n+m−L+1) to SF #(n+m).

(3) Method 3: DAI Based A/N Payload Configuration (DAI Based A/N)

In this method, a DAI indicating a scheduling order value of a PDSCH(e.g., the order of scheduling of the PDSCH in a given SF period)corresponding to DL grant DCI is basically signaled through the DL grantDCI, and a plurality of A/Ns corresponding to N DAI values may betransmitted through one PUCCH (if the DAI has values of 0 to N).Alternatively, in a state in which all DAI values have been divided intoa plurality of DAI groups, a DAI group for which A/N will be transmittedmay be indicated through DL grant DCI. In this case, one DAI value may(commonly) belong to one or more DAI groups. Further, one of theplurality of DAI groups may include all DAI values.

When PDSCH transmission is scheduled in SF #n, for example, as in Method1, in this method, multiple CCA execution opportunities may be given forUL SF #(n+K) corresponding to SF #n and following M UL SF and anoperation of performing A/N PUCCH transmission may be allowed accordingto the CCA result. Here, the value M corresponds to the (maximum) numberof CCA execution or PUCCH transmission opportunities and may beset/indicated through higher layer signaling such as RRC signaling or DLgrant DCI. A UE 1) may perform A/N PUCCH transmission only through a ULSF in which CCA has been initially successfully performed among the M ULSFs or 2) may perform A/N PUCCH transmission through all UL SFs in whichCCA has been successfully performed among the M UL SFs. Accordingly, A/Ninformation corresponding to the same DAI value may be transmittedthrough a plurality of PUCCHs multiple times. Here, A/N informationcorresponding to each DAI value may be reset/repeated per PUCCHtransmission. Whether resetting/repetition is performed may be set by aBS or determined according to intervals of UL SFs in which A/N PUCCHtransmission is performed. For example, when the intervals of the UL SFsare less than a reference value (e.g., Q SFs), A/N informationcorresponding to each DAI may be repeated per PUCCH transmission. Whenthe intervals of the UL SFs are greater than the reference value (e.g.,P SFs), A/N information corresponding to each DAI may be reset per PUCCHtransmission. Q corresponds to the number of DAIS or a multiple thereof.

A case in which A/N information corresponding to a DAI is reset perPUCCH transmission is described. For example, when a decoding resultwith respect to PDSCH reception (DAI=1) in SF #n is ACK, A/N informationcorresponding to DAI=1 may be mapped as ACK only to a payload of a PUCCHinitially transmitted after UL SF #(n+K) including UL SF #(n+K) and A/Ninformation corresponding to DAI=1 may be reset in a payload of a PUCCHtransmitted following the initially transmitted PUCCH. When a decodingresult with respect to PDSCH reception (DAI=1) in SF #n is NACK (orDTX), A/N information corresponding to DAI=1 may be mapped as NACK (orDTX) to a payload of a PUCCH initially transmitted after UL SF #(n+K)including UL SF #(n+K) and A/N information corresponding to DAI=1 may beupdated according to a retransmission data decoding result in a payloadof the PUCCH transmitted following the initially transmitted PUCCH. Whenthere is no new transmission (e.g., PDSCH transmission) corresponding toDAI=1 after A/N information corresponding to DAI=1 is reset, the A/Ninformation corresponding to DAI=1 may be mapped as DTX (or NACK). Onthe contrary, when there is a new transmission (e.g., PDSCHtransmission) corresponding to DAI=1 after the A/N informationcorresponding to DAI=1 is reset, the A/N information corresponding toDAI=1 may be mapped to a decoding result with respect to the newtransmission (e.g., PDSCH transmission).

Alternatively, the UE may operate to always transmit A/N for (all) DAIs(groups) through a PUCCH/PUSCH in all UL SFs irrespective of PDSCHreception/scheduling in an SF corresponding to a UL SF in whichPUCCH/PUSCH transmission is performed (e.g., SF #n corresponding to ULSF #(n+K)). Alternatively, the UE may transmit A/N for (all) DAIs(groups) through a PUCCH/PUSCH only when PDSCH reception/schedulingexists in an SF corresponding to a UL SF in which PUCCH/PUSCHtransmission is performed (e.g., SF #n corresponding to UL SF #(n+K)).Alternatively, the UE may transmit A/N for (all) DAIs (groups) through aPUCCH/PUSCH only when PDSCH reception/scheduling exists in an SF groupcorresponding to a UL SF in which PUCCH/PUSCH transmission is performed(e.g., L SFs of SF #(n−L+1) to SF #n corresponding to UL SF #(n+K)).Here, “when PDSCH reception/scheduling exists” may be limited to casesin which there is A/N corresponding to a specific number of bits (e.g.,X) or more or specific % (e.g., Y %) or more which will be newlytransmitted in a maximum A/N payload (e.g., a total number of A/N bitswhen DAI (group) based A/N is configured for all cells). X and Y arepositive numbers (e.g., integers).

Alternatively, it is possible to indicate whether A/N for (all) DAIs(groups) is transmitted through a PUSCH through a UL grant whichschedules PUSCH transmission or a DL grant which schedules PDSCHtransmission. For example, in a state in which a plurality of cellgroups which are targets of DAI group based A/N feedback has been setthrough higher layer signaling (e.g., RRC signaling) in advance, a cellgroup (PDSCH scheduling therein) for which DAI group based A/N will betransmitted through a PUSCH may be indicated through a UL grant/DLgrant. In the case of multi-SF scheduling method in which multiple PUSCHtransmissions in multiple SFs are simultaneously scheduled throughsingle UL grant DCI transmission, whether A/N is transmitted may beindividually indicated per PUSCH transmission in each SF or whether A/Nis transmitted may be indicated once for PUSCH transmission in all SFs.In the latter case, one indication of whether A/N is transmitted 1) maybe applied to all scheduled PUSCH transmissions, 2) may be applied toonly an initially scheduled/transmitted PUSCH or 3) may be applied to aninitially scheduled/transmitted PUSCH in a group of consecutive SFs whenscheduled SFs are not consecutive.

When transmission of a PUSCH including A/N is scheduled in UL SF #(n+K)as in Method 1, in this method, the UE is given multiple CCA executionopportunities for UL SF #(n+K) and following M UL SF and may be allowedto perform an operation of performing PUSCH transmission according tothe CCA result. Here, the value M corresponds to the (maximum) number ofCCA execution or PUSCH transmission opportunities and may be previouslyset through higher layer signaling such as RRC signaling or indicatedthrough UL grant DCI (which schedules PUSCH transmission in UL SF#(n+K), for example). The UE 1) may perform transmission of the PUSCH(including A/N) only through a UL SF in which CCA has been initiallysuccessfully performed among the M UL SFs or 2) may perform transmissionof the PUSCH (including A/N) through all UL SFs in which CCA has beensuccessfully performed among the M UL SFs. Accordingly, A/N informationcorresponding to the same DAI value may be transmitted through aplurality of PUSCHs multiple times. Here, A/N information correspondingto each DAI value may be reset/repeated per PUSCH transmission. Whetherresetting/repetition is performed may be set by a BS or determinedaccording to intervals of UL SFs in which A/N PUSCH transmission isperformed. For example, when the intervals of the UL SFs are less than areference value (e.g., Q SFs), A/N information corresponding to each DAImay be repeated per PUSCH transmission. When the intervals of the UL SFsare greater than the reference value (e.g., Q SFs), A/N informationcorresponding to each DAI may be reset per PUSCH transmission. Qcorresponds to the number of DAIS or a multiple thereof.

A case in which A/N information corresponding to each DAI is reset perPUSCH transmission is described. For example, when a decoding resultwith respect to PDSCH reception (DAI=1) in SF #n is ACK, A/N informationcorresponding to DAI=1 may be mapped as ACK only to a payload of a PUSCHinitially transmitted after UL SF #(n+K) including UL SF #(n+K) and A/Ninformation corresponding to DAI=1 may be reset in a payload of a PUSCHtransmitted following the initially transmitted PUCCH. When a decodingresult with respect to PDSCH reception (DAI=1) in SF #n is NACK (orDTX), A/N information corresponding to DAI=1 may be mapped as NACK (orDTX) to a payload of a PUSCH initially transmitted after UL SF #(n+K)including UL SF #(n+K) and A/N information corresponding to DAI=1 may beupdated according to a retransmission data decoding result in a payloadof the PUSCH transmitted following the initially transmitted PUSCH. Whenthere is no new transmission (e.g., PDSCH transmission) corresponding toDAI=1 after A/N information corresponding to DAI=1 is reset, the A/Ninformation corresponding to DAI=1 may be mapped as DTX (or NACK). Onthe contrary, when there is a new transmission (e.g., PDSCHtransmission) corresponding to DAI=1 after the A/N informationcorresponding to DAI=1 is reset, the A/N information corresponding toDAI=1 may be mapped to a decoding result with respect to the newtransmission (e.g., PDSCH transmission).

In this method, a plurality of A/Ns corresponding to a plurality of DAIvalues is transmitted through one PUCCH and thus a relatively large UCIpayload size and a large amount of UL control resources may be needed.In consideration of this, when there is only one DAI value scheduledthrough SF #n as an actually scheduled DAI value (corresponding to acase in which a PDSCH signal exists in a reception buffer) among all DAIvalues, an A/N payload in UL SF #(n+K) may be composed of only a singleA/N for SF #n (instead of a plurality of A/Ns for all DAI values)(referred to as “single DAI A/N” hereinafter). Accordingly, when a PDSCHis scheduled for SFs other than SF #n (or DAI values other than the DAIvalue scheduled in SF #n), an A/N payload may be composed of a pluralityof A/Ns for all DAI values (referred to as “all DAI A/N” hereinafter).PUCCH formats (and/or the number of resources) used in single DAI A/Nand all DAI A/N may be differently set/allocated.

Furthermore, an A/N payload configuration method combined with the SFgroup concept of Method 1 is possible. Accordingly, A/N corresponding toa DAI may be configured only for PDSCH scheduling in a specific SFgroup. For example, an A/N payload in UL SF #(n+K) may be composed ofA/N corresponding to a DAI only on the basis of PDSCH scheduling in agroup of SFs of SF #(n+m−L+1) to SF #(n+m).

As another DAI based method, bundled A/N obtained by executing a logicalAND operation on A/Ns corresponding to DAI=1 to a DAI value scheduled inSF #n may be transmitted through a PUCCH in UL SF #(n+K). For PDSCHshaving different reception timings for the same DAI value, A/N for themost recently received PDSCH may be determined as A/N corresponding tothe DAI value. Further, a bundled A/N configuration method realized bycombining the present method and the SF group concept of Method 1 ispossible. For example, A/N corresponding to each DAI value may becalculated for only PDSCH scheduling in an SF group and bundled.

With respect to periodic UCI (e.g., a positive SR or periodic CSI)transmission, multiple CCA execution opportunities through a pluralityof UL SFs may be given in a set UCI transmission period and an operationof performing UCI PUCCH transmission may be permitted according to theCCA result. In addition, the (maximum) number of CCA executionopportunities (the number of PUCCH transmission opportunities accordingthereto) may be set differently at a UCI transmission time according toUCI types (e.g., A/N, positive SR and periodic CSI). For example, amaximum of Na CCA execution (PUCCH transmission) opportunities may begiven for A/N, a maximum of Ns CCA execution (PUCCH transmission)opportunities may be given for SR and a maximum of Nc CCA execution(PUCCH transmission) opportunities may be given for CSI. Here, Na=Ns>Nc,Na>Ns>Nc or Ns>Na>Nc. Here, Nc may be set as Nc=1 (i.e., only one CCAexecution opportunity and PUCCH transmission according thereto arepermitted). When all CCAs for the maximum number of CCA execution (PUCCHtransmission according thereto) opportunities fail, the UE may operateto drop UCI PUCCH transmission.

FIG. 15 illustrates an A/N transmission procedure according to thepresent invention.

Referring to FIG. 15, a UE may receive a PDCCH having uplink schedulinginformation (S1502). Then, the UE may transmit a PUSCH indicated by theuplink scheduling information in a UL SF (S1504). Here, when the PDCCHrequests ACK transmission, the PUSCH may include ACK information aboutan SF set corresponding to the UL SF. The SF set may include a pluralityof SFs. When the PDCCH does not request ACK transmission, the PUSCH doesnot include ACK information about the SF set corresponding to the UL SF.Here, the SF set may include a plurality of consecutive SFs (Method 1).Further, the SF set may include a plurality of SFs corresponding to aplurality of HARQ process IDs (Method 2). Further, the SF set mayinclude a plurality of SFs corresponding to a plurality of DAIs (Method3). Here, the scheduling information includes scheduling informationabout a plurality of PUSCHs, the PDCCH may further include ACK requestinformation, and the ACK request information may be applied only to theinitially scheduled PUSCH among the plurality of PUSCHs. Further, UL andDL transmission resources may be aperiodically configured in wirelesscommunication systems to which the present invention is applied. Inaddition, the present invention may be applied to UCells.

(4) UE-Common Signaling Based Aperiodic SRS Transmission Method

As a method of indicating/performing aperiodic SRS transmission on anycell including a UCell, a method of simultaneously triggering aperiodicSRS transmissions of a plurality of UEs through specific UE-commonsignaling may be considered. For example, in a state in which each bitin a specific DCI format (e.g., DCI format 3/3A) is set to be used toindicate whether aperiodic SRS transmission of an individual UE isperformed (and SRS transmission resources (e.g., an RPB index, atransmission comb and a cyclic shift) and a timing delay between atriggering time and an SRS transmission time), whether aperiodic SRStransmission of a UE is performed, which is set to the correspondingbit, may be indicated according to the value of each bit (e.g., 0 or 1).For example, SRS transmission may be dropped when bit=0 and SRStransmission may be preformed when bit=1. Alternatively, in a state inwhich N different bits (N>1) in DCI are set to be used to indicatewhether aperiodic SRS transmission of an individual UE isperformed/aperiodic SRS transmission timing, whether aperiodic SRStransmission of a UE is performed/aperiodic SRS transmission timing setto corresponding N bits may be indicated according to N bit values. Forexample, if N=2, SRS transmission may be dropped when the values of Nbits are 00 and SRS transmission may be performed at timings 1/2/3 whenthe values of N bits are 01/10/11, respectively. Here, SRS timing may beidentified by an SF and/or a symbol index.

Alternatively, SRS transmission of different resources may be triggeredthrough N bits or SRS transmission based on a combination of differentresources and transmission timings may be triggered through N bits withtiming fixed. In addition, whether SRS transmission is performed and/orresources may be independently triggered per UE through 1 or NUE-specifically allocated bit or bits, and SRS transmission timing maybe commonly set for all UEs through M UE-commonly allocated bits (M>1).Alternatively, in a state in which a plurality of SRS transmissionresource candidates and a plurality of SRS transmission timingcandidates have been previously set through higher layer signaling(e.g., RRC signaling), a resource candidate and a timing candidate to beused for SRS transmission may be indicated through UE-specific signaling(e.g., DCI). Alternatively, the method of indicating one of a pluralityof candidates may be applied to only one of the SRS transmissionresources and timings and the other may be fixed to a deterministicvalue.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that SRS transmission hasbeen triggered all the time. In this case, a bit constituting theUE-common signaling may indicate an SRS transmission resource and/or anSRS transmission timing, and the SRS transmission resource and/or timingmay be indicated by a UE-specific value per UE (e.g., in the case ofresource) or indicated by a UE-common value commonly for all UEs (e.g.,in the case of timing).

UE-common DCI (SRS-trigger DCI for convenience) may be configured suchthat the UE-common DCI is transmitted/detected through an aperiodic SRStransmission cell or a PDCCH CSS on a cell configured to cross-CCschedule the corresponding cell. Further, a specific PDCCH candidate(PC) index of a specific CCE aggregation level (AL) may be allocated forSRS-trigger DCI. In addition, a UE-common RNTI dedicated for SRS-triggerDCI may be allocated. For example, when cases in which the first PCindices of CCE AL 4/8 are allocated for SF-config DCI transmission areconsidered (a total of two cases), 1) the second PC indices (a total oftwo indices) of CCE AL 4/8 and 2) the third PC index of CCE AL 4 and thesecond PC index of CCE AL 8 may be allocated for SRS-trigger DCItransmission. SRS-trigger DCI and UE-specific DCI carrying a DL/UL grantmay indicate different contents while indicating whether aperiodic SRStransmissions at the same timing are transmitted. In this case, the UEmay 1) conform to the contents indicated by the UE-specific DCI carryingthe DL/UL grant or 2) conform to the contents indicated by most recentlydetected DCI.

Alternatively, when specific fields in a UE-specific DCI format carryinga DL/UL grant are set to a combination of specific values, onlyaperiodic SRS transmission may be indicated/performed without DL/UL-SCHTB (Transport Block) transmission. For example, in a state in whichaperiodic SRS transmission has been indicated through DL/UL grant DCI,when a combination of a specific MCS (Modulation and Coding Scheme)index, a specific RV (Redundancy Version) index and/or a specific RA(Resource Allocation) field value is set in the DCI, the UE may performonly aperiodic SRS transmission without DL/UL-SCH TB transmission. Forexample, the combination of specific field values may be set to case 1)in which a code rate based on an MCS/RA combination exceeds a specificlevel, case 2) in which the quantity of resources allocated through RAis equal to or less than a specific level and the MCS index exceeds aspecific value and case 3) in which the RV index is indicated by aspecific value in addition to the condition of case 2.

Additionally, a method of simultaneously triggering aperiodic CSIfeedback transmissions of a plurality of UEs through specific UE-commonsignaling (CSI-trigger DCI for convenience) may be considered. Forexample, in a state in which each bit in a specific DCI format (e.g.,DCI format 3/3A) is set to be used to indicate whether aperiodic CSIfeedback transmission of an individual UE is performed (and CSI feedbacktransmission resources (e.g., PUSCH or PUCCH resources) and a timingdelay between a triggering time and a CSI transmission time), whetheraperiodic CSI transmission of a UE is performed, which is set to thecorresponding bit, may be indicated according to the value of the bit(e.g., 0 or 1). For example, CSI transmission may be dropped when bit=0and CSI transmission may be preformed when bit=1. Alternatively, in astate in which N different bits (N>1) in DCI are set to be used toindicate whether aperiodic CSI feedback transmission of an individual UEis performed/aperiodic CSI feedback transmission timing, whetheraperiodic CSI feedback transmission of a UE is performed/aperiodic CSIfeedback transmission timing set to corresponding N bits may beindicated according to N bit values. For example, if N=2, CSItransmission may be dropped when the values of N bits are 00 and CSItransmission may be performed at timings 1/2/3 when the values of N bitsare 01/10/11, respectively. Here, CSI transmission timing may beidentified by an SF and/or a symbol index.

Alternatively, CSI transmission of different resources may be triggeredthrough N bits or CSI transmission based on a combination of differentresources and transmission timings may be triggered through N bits withtiming fixed. In addition, whether CSI transmission is performed and/orresources may be independently triggered per UE through 1 or NUE-specifically allocated bit or bits, and CSI transmission timing maybe commonly set for all UEs through M UE-commonly allocated bits (M>1).Meanwhile, CSI-trigger DCI and UE-specific DCI carrying a DL/UL grantmay indicate different contents while indicating whether aperiodic CSItransmissions at the same timing are transmitted. In this case, the UEmay 1) conform to the contents indicated by the UE-specific DCI carryingthe DL/UL grant or 2) conform to the contents indicated by most recentlydetected DCI. Alternatively, in a state in which a plurality of CSItransmission resource candidates and a plurality of CSI transmissiontiming candidates have been previously set through higher layersignaling (e.g., RRC signaling), a resource candidate and a timingcandidate to be used for CSI transmission may be indicated throughUE-specific signaling (e.g., DCI). Alternatively, the method ofindicating one of a plurality of candidates may be applied to only oneof the CSI transmission resources and timings and the other may be fixedto a deterministic value.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that CSI feedbacktransmission has been triggered all the time. In this case, a bitconstituting the UE-common signaling may indicate a CSI transmissionresource (e.g., a PUCCH) and/or a CSI transmission timing, and the CSItransmission resource and/or timing may be indicated by a UE-specificvalue per UE (e.g., in the case of resource) or indicated by a UE-commonvalue commonly for all UEs (e.g., in the case of timing).

In addition, similarly to the above-described method, a method ofsimultaneously triggering HARQ-ACK (A/N) feedback transmissions (for DLdata reception at a specific time) of a plurality of UEs throughspecific UE-common signaling may be considered. For example, in a statein which each bit in a specific DCI format (e.g., DCI format 3/3A) isset to be used to indicate whether A/N feedback transmission of anindividual UE is performed (and a PUSCH or PUCCH resource and a timingdelay between a triggering time and an A/N transmission time), whetherA/N feedback transmission of a UE is performed, which is set to acorresponding bit, may be indicated according to the value of thecorresponding bit (e.g., 0 or 1). For example, A/N transmission may bedropped when bit=0 and A/N transmission may be preformed when bit=1.Alternatively, in a state in which N different bits (N>1) in DCI are setto be used to indicate whether A/N feedback transmission of anindividual UE is performed/A/N feedback transmission timing, whether A/Nfeedback transmission of a UE is performed/A/N feedback transmissiontiming set to N corresponding bits may be indicated according to N bitvalues. For example, if N=2, A/N transmission may be dropped when thevalues of N bits are 00 and A/N transmission may be performed at timings1/2/3 when the value of N bits is 01/10/11, respectively. Here, A/Ntiming may be identified by an SF and/or a symbol index.

Alternatively, A/N transmission of different resources may be triggeredthrough N bits or A/N transmission based on a combination of differentresources and transmission timings may be triggered through N bits, withtiming fixed. In addition, whether A/N transmission is performed and/orresources may be independently triggered per UE through UE-specificallyallocated 1 bit or N bits, and A/N transmission timing may be commonlyset for all UEs through UE-commonly allocated M bits (M>1).Alternatively, in a state in which a plurality of A/N transmissionresource candidates and a plurality of A/N transmission timingcandidates have been previously set through higher layer signaling(e.g., RRC signaling), a resource candidate and a timing candidate to beused for A/N transmission may be indicated through UE-specific signaling(e.g., DCI). Alternatively, the method of indicating one of a pluralityof candidates may be applied to only one of the A/N transmissionresources and timings and the other may be fixed to a deterministicvalue.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that A/N transmission hasbeen triggered all the time. In this case, a bit constituting theUE-common signaling may indicate an A/N transmission resource (e.g., aPUCCH) and/or an A/N transmission timing, and the A/N transmissionresource and/or timing may be indicated by a UE-specific value per UE(e.g., in the case of resource) or indicated by a UE-common valuecommonly for all UEs (e.g., in the case of timing).

Additionally, a method of simultaneously triggering PRACH signaltransmissions of a plurality of UEs through specific UE-common signaling(PRACH-trigger DCI for convenience) may be considered. For example, in astate in which each bit in a specific DCI format (e.g., DCI format 3/3A)is set to be used to indicate whether PRACH signal transmission of anindividual UE is performed (and PRACH transmission resources (e.g.,time/code/frequency resources or PRACH preamble index) and a timingdelay between a triggering time and a PRACH transmission time), whetherPRACH signal transmission of a UE is performed, which is set to acorresponding bit, may be indicated according to the value of thecorresponding bit (e.g., 0 or 1). For example, PRACH transmission may bedropped when bit=0 and PRACH transmission may be preformed when bit=1.Alternatively, in a state in which N different bits (N>1) in DCI are setto be used to indicate whether PRACH transmission of an individual UE isperformed/PRACH transmission timing, whether PRACH transmission of a UEis performed/PRACH transmission timing set to corresponding N bits maybe indicated according to N bit values. For example, if N=2, PRACHtransmission may be dropped when the values of N bits are 00 and PRACHtransmission may be performed at timings 1/2/3 when the values of N bitsare 01/10/11, respectively. Here, PRACH transmission timing may beidentified by an SF and/or a symbol index.

Alternatively, PRACH transmission of different resources may betriggered through N bits or PRACH transmission based on a combination ofdifferent resources and transmission timings may be triggered through Nbits with timing fixed. In addition, whether PRACH transmission isperformed and/or resources may be independently triggered per UE through1 or N UE-specifically allocated bit or bits, and PRACH transmissiontiming may be commonly set for all UEs through M UE-commonly allocatedbits (M>1). Meanwhile, PRACH-trigger DCI and UE-specific DCI carrying aPDCCH order may indicate different contents while indicating whetherPRACH transmissions at the same timing are transmitted. In this case,the UE may 1) conform to the contents indicated by the UE-specific DCIcarrying the PDCCH order or 2) conform to the contents indicated by mostrecently detected DCI. Alternatively, in a state in which a plurality ofPRACH transmission resource candidates and a plurality of PRACHtransmission timing candidates have been previously set through higherlayer signaling (e.g., RRC signaling), a resource candidate and a timingcandidate to be used for PRACH transmission may be indicated throughUE-specific signaling (e.g., DCI). Alternatively, the method ofindicating one of a plurality of candidates may be applied to only oneof the PRACH transmission resources and timings and the other may befixed to a deterministic value.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that PRACH transmissionhas been triggered all the time. In this case, a bit constituting theUE-common signaling may indicate a PRACH transmission resource (e.g., aPUCCH) and/or a PRACH transmission timing, and the PRACH transmissionresource and/or timing may be indicated by a UE-specific value per UE(e.g., in the case of resource) or indicated by a UE-common valuecommonly for all UEs (e.g., in the case of timing).

In addition, similarly to the above-described method, a method ofsimultaneously triggering DL CSI measurement RS (CSI-RS) transmissionsof a plurality of UEs through specific UE-common signaling may beconsidered. For example, in a state in which each bit in a specific DCIformat (e.g., DCI format 3/3A) is set to be used to indicate whetherCSI-RS transmission of an individual UE is performed (and CSI-RS signaltransmission resources (e.g., time/code/frequency resources) and atiming delay between a triggering time and a CSI-RS transmission time),whether CSI-RS transmission of a UE is performed, which is set to thecorresponding bit, may be indicated according to the value of the bit(e.g., 0 or 1). For example, CSI-RS transmission may be dropped whenbit=0 and CSI-RS transmission may be performed when bit=1.Alternatively, in a state in which N different bits (N>1) in DCI are setto be used to indicate whether CSI-RS transmission of an individual UEis performed/CSI-RS transmission timing, whether CSI-RS transmission ofa UE is performed/CSI-RS transmission timing set to N corresponding bitsmay be indicated according to N bit values. For example, if N=2, CSI-RStransmission may be dropped when the values of N bits are 00 and CSI-RStransmission may be performed at timings 1/2/3 when the values of N bitsare 01/10/11, respectively. Here, CSI-RS transmission timing may beidentified by an SF and/or a symbol index.

Alternatively, CSI-RS transmission of different resources may betriggered through N bits or CSI-RS transmission based on a combinationof different resources and transmission timings may be triggered throughN bits with timing fixed. In addition, whether CSI-RS transmission isperformed and/or resources may be independently triggered per UE through1 or N UE-specifically allocated bit or bits, and CSI-RS transmissiontiming may be commonly set for all UEs through M UE-commonly allocatedbits (M>1). Alternatively, in a state in which a plurality of CSI-RStransmission resource candidates and a plurality of CSI-RS transmissiontiming candidates have been previously set through higher layersignaling (e.g., RRC signaling), a resource candidate and a timingcandidate to be used for CSI-RS transmission may be indicated throughUE-common signaling or UE-specific signaling (e.g., DCI). Alternatively,the method of indicating one of a plurality of candidates may be appliedto only one of the CSI-RS transmission resources and timings and theother may be fixed to a deterministic value.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that CSI-RS transmissionhas been triggered all the time. In this case, a bit constituting theUE-common signaling may indicate a CSI-RS transmission resource and/or aCSI-RS transmission timing, and the CSI-RS transmission resource and/ortiming may be indicated by a UE-specific value per UE (e.g., in the caseof resource) or indicated by a UE-common value commonly for all UEs(e.g., in the case of timing).

(5) UE-Common Signaling Based Aperiodic SR Transmission Method

As a method of indicating/performing SR transmission for a UL datatransmission resource scheduling request, a method of simultaneouslytriggering SR (e.g., positive SR or negative SR) of a plurality of UEsthrough specific UE-common signaling (in an aperiodic manner) may beconsidered. For example, in a state in which each bit in a specific DCIformat (e.g., DCI format 3/3A) is set to be used to indicate whether SRfeedback transmission of an individual UE is performed (andcorresponding SR transmission resources (e.g., PUCCH resource) and atiming delay between a triggering time and an SR transmission time),whether SR transmission of a UE is performed, which is set to thecorresponding bit, may be indicated according to the value of each bit(e.g., 0 or 1). For example, SR transmission may be dropped when bit=0and SR transmission may be performed when bit=1. Alternatively, in astate in which N different bits (N>1) in DCI are set to be used toindicate whether SR transmission of an individual UE is performed/SRtransmission timing, whether SR transmission of a UE is performed/SRtransmission timing set to N corresponding bits may be indicatedaccording to N bit values. For example, if N=2, SR transmission may bedropped when the values of N bits are 00 and SR transmission may beperformed at timings 1/2/3 when the values of N bits are 01/10/11,respectively. Here, SR timing may be identified by an SF and/or a symbolindex.

Alternatively, SR transmission of different resources may be triggeredthrough N bits or SR transmission based on a combination of differentresources and transmission timings may be triggered through N bits withtiming fixed. In addition, whether SR transmission is performed and/orresources may be independently triggered per UE through 1 or NUE-specifically allocated bit or bits, and SR transmission timing may becommonly set for all UEs through M UE-commonly allocated bits (M>1).Alternatively, in a state in which a plurality of SR transmissionresource candidates and a plurality of SR transmission timing candidateshave been previously set through higher layer signaling (e.g., RRCsignaling), a resource candidate and a timing candidate to be used forSR transmission may be indicated through UE-specific signaling (e.g.,DCI). Alternatively, the method of indicating one of a plurality ofcandidates may be applied to only one of the SR transmission resourcesand timings and the other may be fixed to a deterministic value.

Alternatively, when specific UE-common signaling has been successfullydetected, the UE may operate on the assumption that SR transmission hasbeen triggered all the time. In this case, a bit constituting theUE-common signaling may indicate an SRS transmission resource (e.g.,PUCCH) and/or an SR transmission timing, and the SR transmissionresource and/or timing may be indicated by a UE-specific value per UE(e.g., in the case of resource) or indicated by a UE-common valuecommonly for all UEs (e.g., in the case of timing).

Alternatively, a method of enabling/disabling SR transmission such thata UE periodically performs SR transmission within a specific timeduration through specific signaling may also be considered.Specifically, the UE may operate to perform SR transmission in aspecific period until a disable signal is received upon reception of anenable signal. The SR transmission period may be directly indicatedthrough the enable signal and information about a time duration in which(periodic) SR transmission is permitted may be additionally included inthe enable signal (in this case, additional disable signal transmissionmay be dropped).

With respect to CSI-RS transmission from a BS, a method ofenabling/disabling CSI-RS transmission such that CSI-RS transmissionfrom the BS is periodically performed within a specific time durationthrough specific signaling may also be considered. Specifically, the UEmay operate to perform CSI-RS reception (and related operation) in aspecific period until a disable signal is received upon reception of anenable signal. The CSI-RS transmission period (and/or CSI-RStransmission resource related information) may be directly indicatedthrough the enable signal and information about a time duration in which(periodic) CSI-RS transmission is transmitted may be additionallyincluded in the enable signal (in this case, additional disable signaltransmission may be dropped).

Furthermore, with respect to CSI feedback transmission of the UE, amethod of enabling/disabling CSI transmission such that the UEperiodically performs CSI feedback transmission within a specific timeduration through specific signaling may also be considered.Specifically, the UE may operate to perform CSI feedback transmission ina specific period until a disable signal is received upon reception ofan enable signal. The CSI feedback transmission period may be directlyindicated through the enable signal and information about a timeduration in which (periodic) CSI transmission is permitted may beadditionally included in the enable signal (in this case, additionaldisable signal transmission may be dropped).

In addition, with respect to SRS transmission, a method ofenabling/disabling SRS transmission such that the UE periodicallyperforms SRS transmission within a specific time duration throughspecific signaling may also be considered. Specifically, the UE mayoperate to perform SRS transmission in a specific period until a disablesignal is received upon reception of an enable signal. The SRStransmission period may be directly indicated through the enable signaland information about a time duration in which (periodic) SRStransmission is permitted may be additionally included in the enablesignal (in this case, additional disable signal transmission may bedropped).

The present invention is applicable to LCells operating on the basis ofcontention (between UEs) involving CCA (or specific signal detection)and/or UCells operating without CCA execution as well as UCellsoperating on the basis of CCA. In addition, the present invention isapplicable to TDD systems operating on the basis of dynamicallyreconfigured/indicated DL/UL subframe configurations without dependingon fixed/semi-fixed DL/UL subframe configurations (while operatingwithout additional CCA execution). Furthermore, DL grant DCI may beapplied instead of a specific signal (e.g., PDCCH) UE-commonlytransmitted through a DL SF on a UCell.

FIG. 16 illustrates a BS and a UE of a wireless communication system,which are applicable to embodiments of the present invention.

Referring to FIG. 16, the wireless communication system includes a BS110 and a UE 120. When the wireless communication system includes arelay, the BS or UE may be replaced by the relay.

The BS 110 includes a processor 112, a memory 114 and a radio frequency(RF) unit 116. The processor 112 may be configured to implement theprocedures and/or methods proposed by the present invention. The memory114 is connected to the processor 112 and stores information related tooperations of the processor 112. The RF unit 116 is connected to theprocessor 112 and transmits and/or receives an RF signal. The UE 120includes a processor 122, a memory 124 and an RF unit 126. The processor122 may be configured to implement the procedures and/or methodsproposed by the present invention. The memory 124 is connected to theprocessor 122 and stores information related to operations of theprocessor 122. The RF unit 126 is connected to the processor 122 andtransmits and/or receives an RF signal.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It will beobvious to those skilled in the art that claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present invention or included as anew claim by a subsequent amendment after the application is filed.

In the embodiments of the present invention, a description is madecentering on a data transmission and reception relationship among a BS,a relay, and an MS. In some cases, a specific operation described asperformed by the BS may be performed by an upper node of the BS. Namely,it is apparent that, in a network comprised of a plurality of networknodes including a BS, various operations performed for communicationwith an MS may be performed by the BS, or network nodes other than theBS. The term ‘BS’ may be replaced with the term ‘fixed station’, ‘NodeB’, ‘enhanced Node B (eNode B or eNB)’, ‘access point’, etc. The term‘UE’ may be replaced with the term ‘Mobile Station (MS)’, ‘MobileSubscriber Station (MSS)’, ‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to UEs, eNBs or other apparatuses ofa wireless mobile communication system.

The invention claimed is:
 1. A method performed by a device in awireless communication system, the method comprising: receiving downlinkcontrol information (DCI) for scheduling a physical downlink channel(PDSCH), wherein the DCI comprises delay information related toacknowledgement/negative acknowledgement (A/N) timing; based onreceiving the DCI, receiving data via the PDSCH in a time unit n; andbased on receiving the data in the time unit n, transmitting an A/Npayload in a time unit n+k, where k is one of a plurality of A/N timingvalues and k is based on the received delay information, wherein the A/Npayload comprises a plurality of A/N responses, with the plurality ofA/N responses related to a plurality of data reception occasions, andwherein the plurality of data reception occasions, related to theplurality of A/N responses in the A/N payload, are determined based onall possible values of the delay information for the A/N timing of theplurality of A/N responses in the A/N payload in the time unit n+k. 2.The method of claim 1, wherein each of the plurality of data receptionoccasions is related to a respective time unit n_(i), and wherein n_(i)is an i^(th) element of a timing set that comprises the time unit n. 3.The method of claim 1, wherein a size of the A/N payload is based on anumber of the all possible values of the delay information, regardlessof a number of actually received data associated with the A/N payload.4. The method of claim 1, wherein each time unit comprises a pluralityof contiguous orthogonal frequency division multiplexing (OFDM)-basedsymbols.
 5. The method of claim 1, wherein the DCI is received through aphysical downlink control channel (PDCCH), and wherein the A/N payloadis transmitted through a physical uplink control channel (PUCCH) or aphysical uplink shared channel (PUSCH).
 6. A method performed by adevice in a wireless communication system, the method comprising:transmitting downlink control information (DCI) for scheduling aphysical downlink channel (PDSCH), wherein the DCI comprises delayinformation related to acknowledgement/negative acknowledgement (A/N)timing; based on transmitting the DCI, transmitting data via the PDSCHin a time unit n; and based on transmitting the data in the time unit n,receiving an A/N payload in a time unit n+k, where k is one of aplurality of A/N timing values and k is based on the transmitted delayinformation, wherein the A/N payload comprises a plurality of A/Nresponses, with the plurality of A/N responses related to a plurality ofdata reception occasions, and wherein the plurality of data receptionoccasions, related to the plurality of A/N responses in the A/N payload,are determined based on all possible values of the delay information forthe A/N timing of the plurality of A/N responses in the A/N payload inthe time unit n+k.
 7. The method of claim 6, wherein each of theplurality of data reception occasions is related to a respective timeunit n_(i), and wherein n_(i) is an i^(th) element of a timing set thatcomprises the time unit n.
 8. The method of claim 6, wherein a size ofthe A/N payload is based on a number of the all possible values of thedelay information, regardless of a number of actually received dataassociated with the A/N payload.
 9. The method of claim 6, wherein eachtime unit comprises a plurality of contiguous orthogonal frequencydivision multiplexing (OFDM)-based symbols.
 10. The method of claim 6,wherein the DCI is transmitted through a physical downlink controlchannel (PDCCH), and wherein the A/N payload is received through aphysical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH).
 11. A device configured to operate in a wirelesscommunication system, the device comprising: at least one processor; andat least one computer memory operably connectable to the at least oneprocessor and storing instructions that, when executed by the at leastone processor, perform operations comprising: receiving downlink controlinformation (DCI) for scheduling a physical downlink channel (PDSCH),wherein the DCI comprises delay information related toacknowledgement/negative acknowledgement (A/N) timing; based onreceiving the DCI, receiving data via the PDSCH in a time unit n; andbased on receiving the data in the time unit n, transmitting an A/Npayload in a time unit n+k, where k is one of a plurality of A/N timingvalues and k is based on the received delay information, wherein the A/Npayload comprises a plurality of A/N responses, with the plurality ofA/N responses related to a plurality of data reception occasions, andwherein the plurality of data reception occasions, related to theplurality of A/N responses in the A/N payload, are determined based onall possible values of the delay information for the A/N timing of theplurality of A/N responses in the A/N payload in the time unit n+k. 12.The device of claim 11, wherein each of the plurality of data receptionoccasions is related to a respective time unit n_(i), and wherein n_(i)is an i^(th) element of a timing set that comprises the time unit n. 13.The device of claim 11, wherein a size of the A/N payload is based on anumber of the all possible values of the delay information, regardlessof a number of actually received data associated with the A/N payload.14. The device of claim 11, wherein each time unit comprises a pluralityof contiguous orthogonal frequency division multiplexing (OFDM)-basedsymbols.
 15. The device of claim 11, wherein the DCI is received througha physical downlink control channel (PDCCH), and wherein the A/N payloadis transmitted through a physical uplink control channel (PUCCH) or aphysical uplink shared channel (PUSCH).
 16. A device configured tooperate in a wireless communication system, the device comprising: atleast one processor; and at least one computer memory operablyconnectable to the at least one processor and storing instructions that,when executed by the at least one processor, perform operationscomprising: transmitting downlink control information (DCI) forscheduling a physical downlink channel (PDSCH), wherein the DCIcomprises delay information related to acknowledgement/negativeacknowledgement (A/N) timing; based on transmitting the DCI,transmitting data via the PDSCH in a time unit n; and based ontransmitting the data in the time unit n, receiving an A/N payload in atime unit n+k, where k is one of a plurality of A/N timing values and kis based on the transmitted delay information, wherein the A/N payloadcomprises a plurality of A/N responses, with the plurality of A/Nresponses related to a plurality of data reception occasions, andwherein the plurality of data reception occasions, related to theplurality of A/N responses in the A/N payload, are determined based onall possible values of the delay information for the A/N timing of theplurality of A/N responses in the A/N payload in the time unit n+k. 17.The device of claim 16, wherein each of the plurality of data receptionoccasions is related to a respective time unit n_(i), and wherein n_(i)is an i^(th) element of a timing set that comprises the time unit n. 18.The device of claim 16, wherein a size of the A/N payload is based on anumber of the all possible values of the delay information, regardlessof a number of actually received data associated with the A/N payload.19. The device of claim 16, wherein each time unit comprises a pluralityof contiguous orthogonal frequency division multiplexing (OFDM)-basedsymbols.
 20. The device of claim 16, wherein the DCI is transmittedthrough a physical downlink control channel (PDCCH), and wherein the A/Npayload is received through a physical uplink control channel (PUCCH) ora physical uplink shared channel (PUSCH).